Let's Make Robots!

Servo Tester Using Picaxe 08M

Controls two servos with pots
servopot4.bas3.23 KB
servotst.png4.71 KB

This is my second Picaxe project . It is a simple servo tester or servo cycler built using an 08M . It has 3 modes of operation . In mode 1 each servo is controlled by its own pot . In mode 2 both servos are centered with a 1.5 millisecond pulse . In mode 3 both servos are cycled with the left pot setting the low end point and the right pot setting the high end point . The modes are cycled using a normally open switch . I had to use the pulseout command instead of the servo and servopos commands to avoid jitter .

     I used an enclosure from an old rc toy airplane charger for the case . It was a tight fit for the 4 AA battery box , 2 pots , circuit board etc. The circuit board was made by laser printing onto a label backing sheet and transferring by iron to the pcb . Ferric chloride was used for etching . This was the first time I tried the laser printer method and the results were ok but not great .

    I know you can buy a single channel version of this for a few dollars but I like to make my own stuff . It's really handy for setting up servos without doing any programming . I have included the basic program and schematic for anyone who is interested .

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Nice work. Can you post a schematic of your circuit?


Thanks . I included the schematic as an attachment along with the code . I have edited the post to include the image in the main body . I'm new here so I'm still not sure where to put things .

I have built myself one few months ago. Mine is very simple comparing to yours, it just controls 2 servos with 2 pots. And it is very bulky as I've used my favorite enclosure - lunch box :) I believe this device is a MUST HAVE for a robot hobbyist, and as you have said, preferrably DIY. Thanks a lot for posting! Ah, here is mine:

What processor did you use or did you use a 555 timer . I like food containers as enclosures also . Here is a picture of my FTDI breakout board with a Picaxe programming jack .

Same as you did. 08M rocks! :)

Very handy tool my friend. I also like food containers too,easy to make them waterproof also. Thanks for sharing :)

Check out this link, they are cheap connect servo potentiometer and 6V battery and it works ;-) http://www.mindsetsonline.co.uk/product_info.php?cPath=16_13_530&products_id=1009480

I'm using a Stamp board to compile Servopot4.bas and Im getting th following error: 'serfreq' command not supported in this mode, does it mean I have to get a Picaxe 08M in order to run Servopot4.bas?





I am not familer with your Stamp board . Is it the original Parallax Basic Stamp , also called the Stamp 1 ? The program will not run on a Parallax Stamp . It will run on an Picaxe 08M without change . I haven't tried it yet on an 08M2 . I have some ordered and will post any code updates as soon as I can .

Good luck.

Hey Rick100,

I have experimented with something similar, but with the pots placed on a joystick: PIC-AIM. I struggled with it for a month with no success. Servo jitter was my enemy. The funny thing is that I have collected this page of yours before I started that experiment. It looks as though the answer to my problem has been in "My Collection" all along. I´ve taken a look at your code and your pulseout approach looks promising. I can´t wait to adapt it to my gizmo.

For some reason I remembered this project of yours today...